ok so i make the displace map not even sure im doing that correctly then i go filters>map>displace and "makes sure its selected" how. i need more in depth instructions should the map thinghy be in the other window created by the script how do i select etc all a have is a mass of gray i dont know how to use this please help.

Script doesn't change anything in reflection. It produces map which can then be applied to form the water-like ripples. So, if the original reflection was colorful, it should stay so after map applied.

Since GIMP's displacement map filter accepts separate drawables for the X and Y offsets, wouldn't it be preferable if the script produced two separate channels rather than employing the red and green components of a single layer?